Realism Versus Modernism

Modernism is a late 19th and early 20th century movement that rejected the ideals of realism. It forced its reader/viewers/listeners to think outside the box and look at life in a slightly different way. It was avant-garde or unconventional in it's way of thinking. Artists used fragmented pieces of "reality" to showcase their thought and allowed people to perceive differences in the same piece.

Realism does not need to be photorealistic. It is representational art, as opposed to abstract art, that tends to focus on the realities of everyday life as opposed to an idealized version of life. The movement is generally considered to have begun in Europe in the mid 19th century in opposition to the emotionalism, exaggeration and idealization of Romanticism. (Photorealism is a 20th century offshoot of the larger movement.)

Modernism is thought to have begun in the late 19th century, though this is argued about a lot. Very broadly, one could say that modernism encompasses a rejection of traditional ways of making and defining art accompanied by a kind of glorification of the individual.

While Realism is a strong thread throughout Modernism, Modernism also includes other movements as well, such as non-representational (abstract) art.

Some consider Modernism to have ended after World War II, and that work made after, in reaction to Modernism, is Postmodern. This, however, is highly debatable and a can of worms. It is also not really relevant to your question: Realism is a movement within Modernism.